1GETUSERSHELL(3)            Linux Programmer's Manual           GETUSERSHELL(3)
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NAME

6       getusershell, setusershell, endusershell - get permitted user shells
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SYNOPSIS

9       #include <unistd.h>
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11       char *getusershell(void);
12       void setusershell(void);
13       void endusershell(void);
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15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17       getusershell(), setusershell(), endusershell():
18           Since glibc 2.21:
19               _DEFAULT_SOURCE
20           In glibc 2.19 and 2.20:
21               _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
22           Up to and including glibc 2.19:
23               _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
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DESCRIPTION

26       The  getusershell()  function  returns  the  next  line  from  the file
27       /etc/shells, opening the file if necessary.  The  line  should  contain
28       the  pathname  of a valid user shell.  If /etc/shells does not exist or
29       is unreadable, getusershell() behaves as if /bin/sh and  /bin/csh  were
30       listed in the file.
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32       The setusershell() function rewinds /etc/shells.
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34       The endusershell() function closes /etc/shells.
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RETURN VALUE

37       The getusershell() function returns NULL on end-of-file.
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FILES

40       /etc/shells
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ATTRIBUTES

43       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
44       tributes(7).
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46       ┌──────────────────────────────────────────┬───────────────┬───────────┐
47       │Interface                                 │ Attribute     │ Value     │
48       ├──────────────────────────────────────────┼───────────────┼───────────┤
49       │getusershell(), setusershell(),           │ Thread safety │ MT-Unsafe │
50       │endusershell()                            │               │           │
51       └──────────────────────────────────────────┴───────────────┴───────────┘
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CONFORMING TO

54       4.3BSD.
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SEE ALSO

57       shells(5)
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COLOPHON

60       This  page  is  part of release 5.13 of the Linux man-pages project.  A
61       description of the project, information about reporting bugs,  and  the
62       latest     version     of     this    page,    can    be    found    at
63       https://www.kernel.org/doc/man-pages/.
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67GNU                               2021-03-22                   GETUSERSHELL(3)
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